EUGENE, Ore. — Does legalizing medical marijuana lead to more teens smoking pot? That’s what a new study, co-authored by a University of Oregon researcher, aimed to find out.

“When we thought about it theoretically, we didn’t know what to expect,” said UO assistant professor Benjamin Hansen. “There are certain reasons you might think supply is going up. But there are also reasons you might think demand is going down.”

“Medical Marijuana Laws and Teen Marijuana Use” isn’t the first time Hansen and his co-authors — Daniel I. Rees from the University of Colorado Denver and D. Mark Anderson from Montana State University — tackled an issue related to medical marijuana. They’ve also done studies on its ties to adult pot use and traffic deaths.

“I think a natural progression from that was looking at what happens to teen drug use,” said Hansen.

To do that, the researchers reviewed several national studies, including data from more than 46,000 students, and looked at the numbers in states where medical marijuana is legal.

“There really seems to be no effect,” said Hansen. “Or, if anything, there might be a slight negative one.”

The study’s conclusion is what Cheryl Smith, the executive director of Eugene’s Compassion Center, expected.

“I’m not very surprised [the study’s results],” she said, “but I’m also very pleased because it means the message we’re trying to get out — that marijuana is medicine, not necessarily just a recreational drug — is getting through.”

Some drug counselors doubt the study’s findings. They say legalizing marijuana for medicinal use tells teens pot is on the same plane as cigarettes or alcohol.

“We’re moving more and more toward it being another social-recreational intoxicant,” said Serenity Lane’s Jerry Gjesvold. “Youth, being who they are, they’re going to experiment and they’re going to try.”

But Hansen insisted the proof is in the data: We’ve used the most expansive data sets that are available and the most rigorous techniques around.”

Hansen and his co-authors finished the study in May. It’s now making its rounds through reviews and peer reviews.